Defining Priority Level And Service Class For Wm-Ad Traffic; Defining The Service Class For The Wm-Ad - Extreme Networks Summit WM User Manual

Defining priority level and service class for WM-AD
traffic
Voice over Internet Protocol (VoIP) using 802.11 wireless local area networks are enabling the integration
of internet telephony technology on wireless networks. Various issues including Quality-of-Service
(QoS), call control, network capacity, and network architecture are factors in VoIP over 802.11 WLANs.
Wireless voice data requires a constant transmission rate and must be delivered within a time limit. This
type of data is called isochronous data. This requirement for isochronous data is in contradiction to the
concepts in the 802.11 standard that allow for data packets to wait their turn, in order to avoid data
collisions. Regular traffic on a wireless network is an asynchronous process in which data streams are
broken up by random intervals.
To reconcile the needs of isochronous data, mechanisms are added to the network that give voice data
traffic or another traffic type priority over all other traffic, and allow for continuous transmission of
data.
In order to provide better network traffic flow, the Controller, Access Points and Convergence Software
provides advanced Quality of Service (QoS) management. These management techniques include:
WMM (Wi-Fi Multimedia) - Enabled on individual Altitude AP, the standard provides multimedia
enhancements that improve the user experience for audio, video, and voice applications. WMM is
part of the 802.11e standard for QoS.
IP ToS (Type of Service) or DSCP (Diffserv Codepoint) - The ToS/DSCP field in the IP header of a
frame is used to indicate the priority and Quality of Service for each frame. The IP TOS and/or
DSCP is maintained within CTP (CAPWAP Tunneling Protocol) by copying the user IP QoS
information to the CTP header - this is referred to as Adaptive QoS.

Defining the service class for the WM-AD

Service class is determined by the combination of the following operations:
The class of treatment given to a packet. For example, queuing or per hop behavior (PHB).
The packet marking of the output packets (user traffic and/or transport).
Table 22: Service classes
Service class name (number)
Network Control (7)
Premium (Voice) (6)
Platinum (video) (5)
Gold (4)
Silver (3)
Bronze (2)
Best Effort (1)
Background (0)
The service class is equivalent to the 802.1D UP (user priority) with the exception that its scale is linear:
Summit WM User Guide, Software Version 5.3
Priority level
7 (highest priority)
6
5
4
3
2
1
0 (lowest priority)
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